1. Field of the Invention
This invention relates generally electronic equipment, such as computers, and, more particularly, to apparatus and methods for mounting and cooling circuit boards in racks.
2. Background Information
Computer systems often require high reliability and high capacity of operation. Various approaches have been taken to providing such high-performance, high reliability systems. For example, many computer systems include redundant resources so that if one component of the system develops a fault, the computer system remains operational using the redundant resources.
High density systems are typically rack mountable, with one or more processor modules occupying a prescribed space (e.g., a vertical slot) in the rack. A trend in recent times is to make the computers with smaller form factors. This means that more processors can be located in a rack. This has the advantage of increasing the processing density within the racks, and also the advantage of reducing the distance between the computer systems.
Components of computer systems may generate substantial amounts of heat during operation. Higher operating temperatures in electronic components are associated with decreased reliability of the components. To address this issue, some systems include fans or blowers to force air over the heat-generating components to cool the components. Because the cooling air is heated by the components as it passes over them, the cooling air temperature is warmer when it passes over downstream components (e.g., components near an air outlet in a enclosure) than when the cooling air passes over upstream components (e.g., components near an air inlet in a enclosure). Cooling effectiveness for the downstream components in a system may therefore be reduced.
Many standards have been produced for computer systems and their components. One such standard is the PICMG (PCI Industrial Computer Manufacturers Group) 3.0 specification for advanced telecommunications computing architecture (ATCA). Standards such as PICMG 3.0 may specify physical dimensions or arrangement of elements in a system (e.g., a location, size, or envelope of a circuit board in a rack-mounted system). For example, limits may be placed on a location and “footprint” of a circuit board on a backplane. A standard may also set a limit on the number of node slots in a rack of a given size. For example, in a typical PICMG 3.0 system, a chassis may provide 16 node slots.
It would be desirable to have computer systems that provide more effective cooling of components. It would further be desirable to have computer systems with increased component (e.g., processor) density. It would be further desirable that components of such systems be compatible with industry standards such as PICMG 3.0.